DW, You have a bad solder connection somewhere, and it is not necessarily in the audio section - it can be anywhere in the receive chain, including the noise blanker and the KSB2 option if those are installed.
Use a constant signal source such as a XG1, XG2, XG3 signal generator set for a 50 uV output. Tune in the generator output and make some observations - does the S-meter drop when the audio drops? If so, the problem is prior to the output of the IF amplifier. OTOH, if the S-meter stays constant and the audio drops, the problem is after the IF amplifier output. I can't help much with specifics beyond that to further locate the problem. You might "shotgun" it by re-flowing the soldering with a hot (750 degF) soldering iron - add a tiny bit of flux if necessary. Examine your solder connections carefully. I know nothing of your soldering capability, so please no insult if you are an expert. If your soldering level is expert, the most likely is that you missed a solder connection somewhere. A good solder connection will have the solder flowing out to an almost invisible edge on both the solder pad and the component lead. There may be a small concave fillet at the connection. If your solder looks more like "balls" (convex) or there is a ring around a component lead, that is a problem. 73, Don W3FPR On 9/25/2012 5:20 PM, dw wrote: > Hi Gang, > I got my K2 a couple of years ago. > Once in a great while I would notice the audio volume drop to about 30%. > It would typically happen after I had moved the unit or had the cover > off doing filter alignments. > I found I would simply tap the unit and the audio volume would be > normal. > > I figured I would eventually get around to checking the circuit when I > had the unit cover off again. > > Well last week I replaced the audio and RF gain pots. > Those are working sweetly. > > At the time I had the control PC dis-assembled I did some re-soldering > of all of the joints I could find around the LM380. > > I thought I had it fixed by doing that but last night it did it again. > > Any hints or tips on best way to troubleshoot this? > > Maybe tracing the audio circuit with a signal source at the time it > drops? > Your suggestions welcome!! > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
